Even with their puffy pink blossoms, mimosas still a pest on national park lands

A National Park Service crew spent most of Wednesday, Oct. 26, 2011 doing an exotic plant control project along the Foothills Parkway in Blount Co. Their target was an invader from Asia called mimosa trees growing in a rockface along the parkway.

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National Park Service workers Renee Sniegocki, right, and Troy Evans, left, secured by ropes, work to cut and spray mimosa trees along the Foothills Parkway on Wednesday. The National Park Service crew spent most of the day on an exotic plant control project in Blount County.

The fast-growing mimosas are not native to the East Tennessee backcountry, and they prevent the growth of native species. Ken Culbertson, a forestry technician with the park service, said the plant is a prolific seed producer, allowing entire areas of the park land to become "carpeted" with small trees.
(DAVID MANNING/ASSOCIATED PRESS)

AP2009

TALLASSEE — In some neighborhoods, mimosa trees, with their tiny leaves and puffy pink blossoms, are part of the manicured landscape.

But on East Tennessee lands maintained by the National Park Service they are called "exotic" and "invasive."

That's why a team of forestry personnel with the park service spent a brilliant autumn Wednesday on a rocky hillside sawing mimosa trees off at ground level and spraying the stumps with a chemical to make sure they don't come back.

The fast-growing mimosas are not native to the East Tennessee backcountry, according to Ken Culbertson, a forestry technician with the park service, and they prevent the growth of native species.

"We don't vilify the tree," he said. "This is about preserving the native species."

So the team gathered near the U.S. Highway 129 end of the Foothills Parkway to make the hillside a mimosa-free zone so other plants and trees have a chance to flourish.

Troy Evans, another forestry technician, and Renee Sniegocki, an intern at the Great Smoky Mountains National Park, tied bright orange ropes to trees on the hill, attached the ropes to harnesses they were wearing, lowered themselves down to where the mimosas were growing out of the rocks and began sawing the trees off.

They sprayed a herbicide mixed with a red-dyed, soy-based oil on the fresh stumps to assure the trees would not just spring up again nearby.

Culbertson said mimosas are prolific seed producers, allowing entire areas of the park land to become "carpeted" with small trees. He tells of a recent eradication effort that saw 4,001 trees cut in a 10-acre area.

As the mimosas are cut and poisoned, Evans and Sniegocki were responsible for counting how many they cut and how much of the herbicide they used to gauge "productivity" of the trees and to "determine if the program is working overall," Culbertson said.

Part of the reason the activity takes place this time of year is that the mimosas remain green while native trees making their dazzling annual color shift. That makes mimosas easier to spot. Also, autumn is when the stumps will draw the herbicide deep into the root system to do its work.

Also, there are no wasps nests and fewer snakes to menace the workers in October.

The herbicide, Culbertson said, is one that quickly dissipates in the ground and will not harm nearby growth.

Known as a silk tree, the mimosa is native to Asia and was probably brought to this country as a decorative tree, Culbertson said.

As the mimosas were cut and tossed down the hillside Wednesday, Culbertson and Paul "Doc" Hadala, a retired civil engineering professor who works as a park volunteer, heaved the trees down the slope on the other side of the parkway, where nature will finish the work.